Japanese Unexamined Patent Application Publication No. 10-217818 describes, as a system for restraining an occupant of an automobile in the event of a collision, an occupant restraint device that increases the height or the hardness of a front portion of a sheet cushion in the event of a vehicle collision to prevent the submarine phenomenon in which the occupant slips out from under a lap belt in the collision even when the occupant wears a seat belt.
FIG. 13 is a vertical cross-sectional view in the anteroposterior direction of a seat, illustrating the occupant restraint device according to the above publication. In a front portion of the seat, an airbag 44 is disposed between a seat pan 40 and a seat pad 42. The airbag 44 extends in the lateral width direction of the seat, and is inflatable by an inflator 46. The upper surface of the seat pad 42 is covered by a trim cover 48, on which the occupant sits.
When the inflator 46 is activated in the vehicle collision, the airbag 44 inflates. Thereby, a front portion of the seat pad 42 is pushed up, or is thrust up from beneath to have an increased density. Accordingly, forward movement of the body of the occupant is prevented (suppressed).
A stud bolt 50 projects downward from the inflator 46 inside the airbag 44. The bolt 50 pierces through the airbag 44 and the seat pan 40 to project downward from the seat pan 40. With a nut 52 screwed on the bolt 50, the inflator 46 is fixed to the seat pan 40, and the airbag 44 is sandwiched and fixed between the inflator 46 and the seat pan 40.
Patent Document Japanese Unexamined Patent Application Publication No. 10-217818
In the occupant restraint device according to the above Japanese Unexamined Patent Application Publication No. 10-217818, the stud bolt 50 of the inflator is located at the center in the anteroposterior direction of the airbag 44 (on the center line passing through the center in the anteroposterior direction of the airbag 44 and extending in the lateral direction).
Recently, the seat has become multifunctional. Thus, with a variety of structures laid out under the seat, the space for accommodating the airbag has been reduced.